The present invention relates to a centrifugal pump. More particularly, the present invention relates to a self-priming centrifugal pump.
A centrifugal pump works by increasing the pressure of a fluid using a rotating impeller. Typically, a liquid enters the pump at or near an axis of rotation and is accelerated by the impeller. The liquid then flows radially outwards into downstream piping.
A centrifugal pump is not self-priming, and various mechanisms for providing self-priming centrifugal pumps have been developed.
Most commonly, a self-priming centrifugal pump is provided with a discharge tank contained in the pump housing and connected to recirculate liquid through the pumping chamber for priming. These tanks are initially provided with a supply of the liquid to be pumped and, during priming, the pump impeller is rotatably driven to recirculate liquid from the tank through the pumping chamber, so that gas in the pumping chamber becomes entrained with the recirculated liquid.
In other designs, an additional external pump is provided solely for priming. For example, a liquid piston pump, functioning as a priming wheel, may be provided for this purpose.
EP 1505301 discloses a further self-priming centrifugal pump design. In this design, a diaphragm is provided in the liquid flow path and driven with reciprocating motion to provide the priming. After the pump has been primed, the diaphragm may be disengaged using a clutch.
There is a continuing need for a compact, efficient and effective self-priming centrifugal pump design.